w1: add 1-wire master driver for i.MX27 / i.MX31

This patch adds support for the 1-wire master interface for i.MX27 and
i.MX31.

Signed-off-by: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 219 insertions, 0 deletions

diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
index 90616822cd20..96d2f8e4c275 100644
--- a/drivers/w1/masters/Kconfig
+++ b/drivers/w1/masters/Kconfig
@@ -34,6 +34,12 @@ config W1_MASTER_DS2482
           This driver can also be built as a module.  If so, the module
           will be called ds2482.
 
+config W1_MASTER_MXC
+        tristate "Freescale MXC 1-wire busmaster"
+        depends on W1 && ARCH_MXC
+        help
+          Say Y here to enable MXC 1-wire host
+
 config W1_MASTER_DS1WM
         tristate "Maxim DS1WM 1-wire busmaster"
         depends on W1 && ARM && HAVE_CLK
diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
index bc4714a75f3a..c5a3e96fcbab 100644
--- a/drivers/w1/masters/Makefile
+++ b/drivers/w1/masters/Makefile
@@ -5,6 +5,8 @@
 obj-$(CONFIG_W1_MASTER_MATROX)          += matrox_w1.o
 obj-$(CONFIG_W1_MASTER_DS2490)          += ds2490.o
 obj-$(CONFIG_W1_MASTER_DS2482)          += ds2482.o
+obj-$(CONFIG_W1_MASTER_MXC)             += mxc_w1.o
+
 obj-$(CONFIG_W1_MASTER_DS1WM)           += ds1wm.o
 obj-$(CONFIG_W1_MASTER_GPIO)            += w1-gpio.o
 obj-$(CONFIG_HDQ_MASTER_OMAP)           += omap_hdq.o
diff --git a/drivers/w1/masters/mxc_w1.c b/drivers/w1/masters/mxc_w1.c
new file mode 100644
index 000000000000..b9d74d0b353e
--- /dev/null
+++ b/drivers/w1/masters/mxc_w1.c
@@ -0,0 +1,211 @@
+/*
+ * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Luotao Fu, kernel@pengutronix.de
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_log.h"
+
+/* According to the mx27 Datasheet the reset procedure should take up to about
+ * 1350us. We set the timeout to 500*100us = 50ms for sure */
+#define MXC_W1_RESET_TIMEOUT 500
+
+/*
+ * MXC W1 Register offsets
+ */
+#define MXC_W1_CONTROL          0x00
+#define MXC_W1_TIME_DIVIDER     0x02
+#define MXC_W1_RESET            0x04
+#define MXC_W1_COMMAND          0x06
+#define MXC_W1_TXRX             0x08
+#define MXC_W1_INTERRUPT        0x0A
+#define MXC_W1_INTERRUPT_EN     0x0C
+
+struct mxc_w1_device {
+        void __iomem *regs;
+        unsigned int clkdiv;
+        struct clk *clk;
+        struct w1_bus_master bus_master;
+};
+
+/*
+ * this is the low level routine to
+ * reset the device on the One Wire interface
+ * on the hardware
+ */
+static u8 mxc_w1_ds2_reset_bus(void *data)
+{
+        u8 reg_val;
+        unsigned int timeout_cnt = 0;
+        struct mxc_w1_device *dev = data;
+
+        __raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL));
+
+        while (1) {
+                reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL);
+
+                if (((reg_val >> 7) & 0x1) == 0 ||
+                    timeout_cnt > MXC_W1_RESET_TIMEOUT)
+                        break;
+                else
+                        timeout_cnt++;
+
+                udelay(100);
+        }
+        return (reg_val >> 7) & 0x1;
+}
+
+/*
+ * this is the low level routine to read/write a bit on the One Wire
+ * interface on the hardware. It does write 0 if parameter bit is set
+ * to 0, otherwise a write 1/read.
+ */
+static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
+{
+        struct mxc_w1_device *mdev = data;
+        void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL;
+        unsigned int timeout_cnt = 400; /* Takes max. 120us according to
+                                         * datasheet.
+                                         */
+
+        __raw_writeb((1 << (5 - bit)), ctrl_addr);
+
+        while (timeout_cnt--) {
+                if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1))
+                        break;
+
+                udelay(1);
+        }
+
+        return ((__raw_readb(ctrl_addr)) >> 3) & 0x1;
+}
+
+static int __init mxc_w1_probe(struct platform_device *pdev)
+{
+        struct mxc_w1_device *mdev;
+        struct resource *res;
+        int err = 0;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res)
+                return -ENODEV;
+
+        mdev = kzalloc(sizeof(struct mxc_w1_device), GFP_KERNEL);
+        if (!mdev)
+                return -ENOMEM;
+
+        mdev->clk = clk_get(&pdev->dev, "owire_clk");
+        if (!mdev->clk) {
+                err = -ENODEV;
+                goto failed_clk;
+        }
+
+        mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;
+
+        res = request_mem_region(res->start, resource_size(res),
+                                "mxc_w1");
+        if (!res) {
+                err = -EBUSY;
+                goto failed_req;
+        }
+
+        mdev->regs = ioremap(res->start, resource_size(res));
+        if (!mdev->regs) {
+                printk(KERN_ERR "Cannot map frame buffer registers\n");
+                goto failed_ioremap;
+        }
+
+        clk_enable(mdev->clk);
+        __raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
+
+        mdev->bus_master.data = mdev;
+        mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;
+        mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit;
+
+        err = w1_add_master_device(&mdev->bus_master);
+
+        if (err)
+                goto failed_add;
+
+        platform_set_drvdata(pdev, mdev);
+        return 0;
+
+failed_add:
+        iounmap(mdev->regs);
+failed_ioremap:
+        release_mem_region(res->start, resource_size(res));
+failed_req:
+        clk_put(mdev->clk);
+failed_clk:
+        kfree(mdev);
+        return err;
+}
+
+/*
+ * disassociate the w1 device from the driver
+ */
+static int mxc_w1_remove(struct platform_device *pdev)
+{
+        struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
+        struct resource *res;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+        w1_remove_master_device(&mdev->bus_master);
+
+        iounmap(mdev->regs);
+        release_mem_region(res->start, resource_size(res));
+        clk_disable(mdev->clk);
+        clk_put(mdev->clk);
+
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver mxc_w1_driver = {
+        .driver = {
+                   .name = "mxc_w1",
+        },
+        .probe = mxc_w1_probe,
+        .remove = mxc_w1_remove,
+};
+
+static int __init mxc_w1_init(void)
+{
+        return platform_driver_register(&mxc_w1_driver);
+}
+
+static void mxc_w1_exit(void)
+{
+        platform_driver_unregister(&mxc_w1_driver);
+}
+
+module_init(mxc_w1_init);
+module_exit(mxc_w1_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Freescale Semiconductors Inc");
+MODULE_DESCRIPTION("Driver for One-Wire on MXC");